Perhaps you should try some spelling variations:
phuong trinh » chuong trinh, cong trinh, huong tran
dong phuong » duong phuong, dung phuong, dong huong
hieu quang » thieu quang, hieu quan, hieu qua
trinh toan » tinh toan, thanh toan, trinh han
hieu sang » chieu sang, hieu lang, nhieu tang
trang cua » tranh cua, tang cua, thang cua
trung cua » truong cua, trung tuan, trung cap
toan tap » toan ban

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) or (hieu quang)) - hanh ((trang cua) OR (trung cua)) dong phuong trinh toan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - hanh ((trang cua) OR (trung cua)) dong phuong trinh toan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) or (hieu quang)) - hanh ((trang cua) OR (trung cua)) dong phuong trinh toan tap".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) or (hieu quang)) - hanh ((trang cua) OR (trung cua)) dong phuong trinh toan tap*.